Signaling system for railroads



May 21, 1935. T, BQDDE 2,002,468

SIGNALING SYSTEM FOR RAILROADS Filed Oct. 15, 1930 2 4.5 45 H: 7 25 5 I 5 I I. 5 o

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Patented May 21, 1935 SIGNALING SYSTEM FOR musicians Theodore Boddc, Rochester, N. Y., assignor to General N. Y.

Railway Signal Company, Rochester,

Application October 15, 1930, Serial No. 48.8.89"?

17 Claims; (01. 246-4 1) v This invention relates to track circuits for railway signaling systems, and more particularly to a track relay having operating characteristics to compensate for ballast resistance variations.

By a track circuit is: meant an insulated section of railway track having a track battery connected across'the rails at one end and having a track relay connected across the rails at the other end, so that a passing train will establish a shunt across the relay and battery, thus shunting a large part of the current away from the relay. practice the ballast resistance, that is, the resistance between. the track rails through the ties, the ballast, such as cinders or crush stone, and through the ground, varies considerably in accordance with weather conditions. That is, during wet weather more leakage current can flow from one rail to another than there can during dry weather. For this reason, a track circuit having its usual series resistance and the operating characteristics of the relay adjusted for wet weather may not drop in response to the approach of a train during dry weather, and vice versa. In other words, it is necessary for a track circuit maintainer to adjust the trackcircuits over which he has supervision periodically'especially during those seasons when the ballast resistance is extremely variable, and if this is not done the track relay may not pick up after the passage of the train during wet weather, and the track relay may not drop uponthe approach of. a

train during dry weather.

In view of the above and other important considerations; it is proposed in accordance with the present invention to employ a relay which has a slow acting characteristic for adjusting the pick up and drop away'values of the relay in accordance the average current flowing through this relay for an appreciable period of time, say several hours. In other words, it is proposed to construct the relay in such a manner that if the'relay is highly energized for several hours that the drop away values at which the relaywill operate will be much higher than if the relay energized with current of a small value for tin-appreciable period of time. Putting it another way, the quick acting armature of the re lay will have operating characteristics depending on a slow acting compensating element on the relay. More specifically, it is proposed to employ aself adjusting residual pin, in accordance with the particular construction illustrated, which varies the air gap of the relay in accordance with the-difference of temperature between the relay coiland the surrounding atmosphere.

Other objects, purposes and characteristic features of the invention will in part be. obvious from the. accompanying drawing and will in part be pointed outmore specifically hereinafter.

In describing the invention in detail reference will be made to the accompanying drawing, in which Fig. 1 illustrates a track circuit of the usual construction includinga track relay embodying the present invention; I

Fig. 2 shows an enlarged detailed structural view of the novel relay employed in the track circuit of Fig. 1,; V

Fig. 3 illustrates a residual pin of modified construction. i

Fig.4 illustratesa relay employing the features illustratedin Figs. 3 and 5'. i ig. 5 showsa portion of the relay of Fig. F1 on an enlarged scale; and

Fig.6 shows still another modified form of the invention.

Referring to Fig. l of the drawing, a railway track having rails l are shown divided into blocks by insulating ioints 2., of. which only the complete. block I has. been illustrated. The direction of traflic over, the block I is preferably from left to right. as indicated by the arrow, although the track circuit will also function for traffic moving in the opposite'direction. At the exit end of the blockI is provided. the usual track battery 3 and the usualv seriestrack circuit resistance 4,. and the entrance end of the block I has been illustrated a track relay T embodying the present invention, connected between the rails thereof.

Thistrack relay T '(see Fig. 2) is of novel construction but includes the usual magnetic yoke, which as illustrated is made up of two coremembers 5 and 6 bridged at the top with a back yoke 1, all constructed of good quality soft iron such as Norway iron. This core structure 5-6-1 may. have a coil surrounding one or more of its core members 5 and 6, but as shown contains only a .coil 8 on the' core 5. This core structure 56-! is preferably supported in a relay housing on a suitable support, such as the non-magnetic metallic base plate 9. This base plate 9 throughthe medium ofa suitable bracket [0 pivotallyisupports the armature II as by a pivot [2, so that the armature may be attracted to the core structru'e 5-6-l upon energization of the coil 8. The armature I I has fastened thereto but insulated therefrom one or more movable contacts [3 which may cooperate with front and back stationarypontacts, .such as contacts M and l5 'I'he structure thus far described is the typical structure of a track relay of the prior art not provided with the compensating means heretofore mentioned.

The compensating feature of the relay T shown, resides in the provision of an automatically adjusted residual pin comprising a rod 20, constructed of suitable material having a very high thermal co-efiicient of expansion, such as-hard rubber, aluminum or brass. If hard rubber compensating means such as has been illustrated in Fig. 2 is employed, the end of the hard rubber rod 20 is preferably provided with a metal cap 2| screw fastened thereto, to resist wear due to engagement of the armature H therewith. This residual pin preferably consisting of a hard rubber rod 2?) passes through a small hole extending through the core 5, as shown, and it is therefore apparent that the temperature of the rod 20 will depend upon the temperature of the .coil 8, and in turn depend on the extent of current flow in the coil 8 over a long period of time. In order, however, to avoid the capped end 21 of the residual pin assuming a. position also depending upon the temperature of the surrounding air, compensating rods 22 and 23 have been provided. These compensating rods 22 and 23 are exactly of the same length and the same mate-rial as is rod 20, and since the expansion of rods 22 and 23 lift the support 24 carrying the residual pin 29, the net change in the position of the cap 2| will depend upon the difference between the temperature within the core and the temperature of the surrounding air as evidenced by the expansion of rods 22 and 23. In other words, if the temperature of the residual rod 20 is high as compared with the temperature of the rods 22 and 23, the cap 2| on the rod 20 will assume a lower position, and thereby the air gap between the armature II and the cores 5 and B will be larger than it will when this difference of temperature is not as high.

Let us now observe how the novel relay of the present invention will function satisfactorily under wet as well as dry ballast conditions of the track circuit in which it is contained. Let us first assume that the leakage current through the ballast is very high, as is true in the early spring when the ballast is very wet, and that for this reason the voltage applied to the track relay T is very low, this because of the increased current drawn from the battery 3 through the limiting resistance 4 and the track rails I. This decrease of current flow in the coil 8 of the track relay T will gradually cause the rod 20 to cool with respect to the temperature of the rods 22 and 23, thereby causing the residual pin 20-2l to shorten, thereby causing the armature H to draw up closer to the cores 5 and 6, so that the armature I I will not dropin spite of the gradual decrease of current flow in the coil 8. If the decrease of current had been very rapid, as by the approach of a train the armature ll would have dropped before the compensating residual rod 292l would have had suflicient time to cool and contract.

Let us now, on the other hand, assume that it does not rain for many days or even weeks, and the ballast resistance becomes very high and there is very little, if any, leakage current flowing from one rail to the other through the ballast and ties. Under this condition, the voltage applied to the track relay T gradually increases, and in so doing gradually increases the temperature within the core 5'reflected by the length of the rod 20' as compared with the surrounding air temperature reflected by the length of the rods 22 and 23. This increase of temperature of the rod 20, as compared with the rods 22 and 23 will cause the cap 2! of the residual rod 20 to assume a much lower position, thereby increasing the air gap between the armature l I and the cores 5 and 6, so that the relay T will drop away much more readily than. it would before, so that the approach of a train will effect dropping of the track relay T even though a considerable amount of current is still flowing in the coil 8 by reason of the high voltage on the track circuit.

It is thus seen that the relay under consideration, has inherent characteristics to adjust its drop away characteristic in accordance with the average amount of current flowing during a preceding comparatively long period of time, of say from five minutes to one or more hours, so that I the effect of a train entering a track circuit upon the track relay will be substantially the same irrespective of the exact degree of energization of the track circuit and its relay. It is of course understood that the presence of a train in a block will have some effect upon the compensating action of the relay, in that the shunting action of the train will cause gradual cooling of the core 5 and the residual rod 28, but in practice it has been found that trains usually do not occupy a particularly track circuit for more than a minute or two, and this short period of occupancy will not materially change the temperature of the rod 20, so that the air gap of the relay will, as a matter of fact, be adjusted in accordance with the voltage of the track circuit, and if the battery 3 is a storage battery and. is properly maintained and charged, the adjustment of the relay T will be substantially in accordance with the ballast conditions of the track circuit.

Instead of only adjusting the drop away value of the relay T, that is adjusting the residual pin to cause the armature H to drop away at a particular current value, the relay of Fig. 1 may be provided with a metal spool 2 I as shown in Figs. 3 and 4 of the drawing, in which the head 2| will also adjust the pick-up value of the relay. This feature of automatically adjusting both the drop away and the pick-up characteristic of the relay is deemed desirable and advantageous, in that it enables the track relay to again pick up after it has been dropped by a passing train, even though the ballast leakage is very high and the current that may reach the track relay T, very low.

Instead of using the heat generated in the main coil 8 of the relay shown in Fig. 2, an auxiliary heating element may be employed to heat the residual rod 28. One way of carrying out this modified construction of the invention has been illustrated in Figs. 4 and 5, in which the rod 20 comprising suitable material having a high temperature co-efficient of expansion, has a double thread cut thereon and is 'cross drilled at the lower end as shown by the hole 20 through which hole a suitable resistance wire is passed. The two ends of the wire are then wrapped each in its own thread about the rod 20 so that the result is a non-inductive coil wound in the two threads on the rod 28 This coil which terminates in lead wires 20 and 20 is preferably connected in series with the coil 8 of the relay as shown in Fig. 4, so that the extent of heating is dependent upon the flow of current in the main coil and in turn upon the average potential across the track rails. The circuit through the relay may be traced as follows:battery 3, resistance rail Lwires 3!, 20 ,26 and 3! (see Figs. 4' and 5), coil 8, wire 32, back to the battery 3 through the other rail (see Fig. 1). Also, this series arrangement of these coils is preferably employed so "that any failure of the heating coil surromiding the rod 26 will be checked by dropping of the track relay T. Furthermore, if desired this heating coil may be insulated electrically and also to restrict thefiow of heat away from the rod 20 intothe core 6, as illustrated by the sleeve 10 constructed of suitable electric insulating material or low heat conducting qualities. 'The sleeve 10 may of course be omitted, if desired.

Let us now refer to Fig. 6 which shows a still furthermodified structure. Inthis construction the heat responsive element is the thermal wire 35, which wire upon heating expands and allows the compression coil spring 36 to push the residual plug 31 to' a position to increase the air gap of the relay; wire 35 preferably comprises an' alloy of eighty-live percent copper, thirteen percent manganese and two percent aluminum, which alloy has bothof the two desired charac teristicsynamely, a high coeflicient of electrical resistance and a high temperature coefficient of expansion. Each end of the wire 35 is provided witha knot, which knots rest in a countersink in the plug 31' and the countersink in the screw 38-, respectively, the screw 38 being threaded into bolt 39* threaded into the support 24 and secured by the lock'nut M. The screw is smallenough to pass through the hole in the core 5 for the purpose of assembling. The thermal wire 35 is preferably heat insulated from the core 5, as by a dead air space M, and further the wall through the core 5 is preferably plated with copper, or other suitable metal, for reflecting the heat radiated from the wire back to this same wiren35. The compensating rods 22: and 23 are made of the same material as is the wire 35, or of other suitablematerial having the same temperature coefiicie'nt or expansion, this to c'ompensate for changes in temperature of the surrounding air. These rods 22 and 23 are insulated from the support by insulating sleeves 42 and 43, respectively. Since the wire '31] is soldered to the support 24, the'circu'it through: the relay of Fig. 6 may be traced as follows:--beginning at the wire (see Fig.6), the support 9, spring 36-, residual plug 31, thermal wire 35, screw 38, bolt 38, support 24, wire 45, coil 8 and wire 32; The construction illustrated in Fig. '6 has certain advantageous characteristics, the principalfeature being the compactness'of the thermal element, which allows the electrical energy to be concentrated, thus resulting ina more eflicient relay. Also, in the construction shown in Fig. 6 the compensating element 35 need not necessarily be connected in series with the coil 8 for checking purposes, as mentioned in connection with the forms shown in Figs. 2 and 4, as the rupture of the resistance wire 35 is on the'side of safetyiri that it will cause the armature to drop by the action of the spring 36.

Having thus shown and described one particular embodiment of the present invention, it is desired to be understood that the particular construction illustrated has been selected for the purpose of disclosing the underlying principles of the invention, and has not been selected with the intent of showing the exact construction preferably employed in practicing the invention nor has it been selected for the purpose of showing the scope of the invention, and it is desired to be understood that various changes, modifications and additions'may be made to adapt the invention to the particular problem encountered inpracticing the same, for instance, the same features may be applied to an alternating current relay of the induction type by making suitable changes, and may likewise be applied to a relay'of the polar type, further, if. desired, the coil 8 and the core 5 may be heat insulated, if desired, so that a greater difference of temperature between the rod 23 and the rods 22 and 23 may be obtained, and'also, the time delay in the position of'the residual cap H as compared with the. time at which the change in current flow took place may be increased, all without departing from the spirit or scope of. the present invention or the ideaof' means underlying the same, except as demanded by the: scope of the following claims.

What I claim as new is:

1. In combination, a track circuit including track. rails having a section insulated from adjacent sections, a track battery connected across the rails at one end thereof, and a compensated track relay connected across the rails at the. other end comprising, a. quick acting means including a main coil, and slow acting means included in the same circuit with said quick acting means for changing the operating characteristic of said quick acting means in accordance with the flow of current in said main coil.

2. In combination, a. relay, an energizing circuit' which applies gradually changing variable terminal voltages to the relay, the relay including, in combination, a soft iron. armature, an electro-magnet for picking up and dropping said armature, a residual pin for limiting. the movement of said armature toward said electro-magnet, and automatically controlled means controlled by the voltage applied to said relay for adjusting the effective length of said pin.

j 3.; In combination, a relay, an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, in combination, a soft iron armature, an electro-magnet for picking up and dropping said armature, aresidual pin for, limiting the movement of said armature toward said electro-magnet, and automatically controlled means for adjusting the effective length of said pin in accordance with the average potential applied to said electro-magnet. during a predetermined elapsed period of time.

4. In combination, arelay, an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, in combination, a soft iron armature, an electromagnet for picking up'and dropping said armature, a residual pin for limiting the movement of said armature toward said electro-magnet, and electrically heated thermal responsive means for adjusting the effective length of said pin in accordance with the average'potential applied to said electro-magnet during. a. predetermined elapsed period of time;

5. In combination, a relay, an energizing circuit which applies gradually changing, variable terminal voltages to the relay, the relay including, :in combination, a soft iron armature, an electro-magnet for picking up-and dropping said armature toward and away from said electromagnet, and electrically heated thermal responsive means compensated against changes in the temperature of the surrounding air for adjusting the effective length of said pin in accordance with the average potential applied to said electromagnet during a predetermined elapsed period of time.

6. In combination, a relay, an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, in combination, a soft iron armature, an electro-magnet forpicking up and dropping said armature, a residual pin for limiting the movement of said armature toward said electro-mag net, and electrically heated thermal responsive means having a heating coil connected in series with i said electro-magnet and compensated against changes in the temperature of the surrounding air for adjusting the effective length of said pin in accordance with the average potential applied to said electro-magnet during a predetermined elapsed period of time.

'7. In combination, a relay, an energizing circuit which applies gradually changing variable terminal'voltages to the relay, the relay including, thermal responsive means for changing the drop away characteristic of said relay in accordance with the average current that was flowing during a predetermined elapsed period of time, said thermal responsive means being compensated against ambient temperature changes.

8. In combination, a relay, an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, thermal responsive means for changing the pick-up and the drop-away characteristic of said relay in'accordance with the average current that was flowing during a predetermined elapsed period of time, said thermal responsive means being compensated against surrounding air temperature changes.

9; In combination, a relay, an energizing circuit-which applies gradually changing variable terminal voltages to the relay, the relay including, in combination, a soft iron armature, an electro-magnet for picking up and dropping said armature, a residual device for limiting the movement of said armature toward and away from said electro-magnet, and automatically controlled means controlled by said variable terminal voltage for adjusting the effectiveness of said device. 1 I

10. In combination, a relay,'an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, in combination, a soft iron armature, an electromagnet for picking up and dropping said armature, a residual device for limiting the movement of said armature toward and away from said electro-magnet, and automatically controlled means for adjusting the effective limits of said device in accordance with the average potential applied to said electro-magnet during a predetermined elapsed period of time.

' 11. In combination, a relay, an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, in combination, a soft iron armature, an electro-magnet for picking up and dropping said armature, a residual device for limiting the movement of said armature toward and away from said electro-magnet, and electrically heated thermal responsive means for adjusting the effective position of said device in accordance with the average potential applied to said electromagnet during a predetermined elapsed period of time.

12. In combination, a relay, an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, in combination, a soft iron armature, an electro-magnet for picking up and dropping said armature, a residual device for limiting the movement of said armature toward and away from said electro-magnet, and electrically heated thermal responsive means compensated against changes in the temperature of the surrounding air for adjusting the effective position of said device in accordance with the average potential applied to said electro-magnet during a predetermined elapsed period of time.

13. In combination, a relay, an energizing circuit which applies gradually changing variable terminalvoltages to the relay, the relay including, in combination, a soft iron armature, an electromagnet for picking up and dropping said armature, a headed residual pin for limiting the movement of said armature toward and away from said electro-magnet, and electrically heated thermal responsive means having a heating coil connected in series with said electro-magnet and compensated against changes in the temperature of the surrounding air for adjusting the effective length of said pin inaccordance with the average potential applied to said electro-magnet during a predetermined elapsed period of time.

14. In combination, a relay, an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, a thermal responsive device comprising, an electrically heated device for operating suitable means in accordance with the temperature of said device, and a reflector for preventing the escape of heat so shaped as to reflect radiated heat back into said device.

15,. In combination, a relay, an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, a thermal responsive device comprising, a cylindrical tube having its inside surface constructed to efficiently reflect heat waves, and an electrically heated thermal responsive means located in the axis of said tube.

16. In combination, a relay, an energizing circuit which applies gradually changing variable terminal voltages to the relay, the relay including, a thermal responsive device comprising, a cylindrical tube having its inside surface constructed to efliciently reflect heat waves, and a cylindrical wire having its axis located in the axis of said tube.

17. In combination; a railway track section limited in its length by insulating joints; a source of current connected across the rails at one end of saidsection; a track relay connected across the rails at the other end of said section comprising, a winding, a soft iron armature, and slow-acting regulating means including a variable magnetic path containing said armature for varying in small increments the sensitivity of said relay in accordance with gradual changes of voltage across the rails at the relay end of said track section.

THEODORE BODDE. 

